Conventionally, as a device for informing an automobile driver about a dangerous state or a safety state, the device judges whether a driver recognizes a traffic environment or not and informs him/her about risk factors depending on the level of the recognition.
FIG. 11 is a schematic view of the conventional safety-drive assistance device. The safety-drive assistance device judges a direction to which a driver pays attention as a necessarily watched direction, obtains watching frequencies as how often a driver looks at the necessarily watched direction and judges whether a driver recognizes a traffic environment using such frequencies (see the patent document 1).
FIG. 12 is a schematic view of the other conventional safety-drive assistance device. This safety-drive assistance device judges a watched point from a driver's visual-line direction, defines a watched area as a neighborhood around the watched point and judges whether a driver recognizes a states of road facilities or not depending on whether these road facilities exist within the watched area or not (See the patent document 2).
In case of informing an automobile driver about any possibilities of risks such as a collision, a rear-end collision, and contacting with a pedestrian, it is desirable that a device warn a driver when it is necessary. Namely, it is not necessary that a device warns a driver about a dangerous state if he/she already knows such state. Such warning gives a driver bothersome if he/she receives unnecessary warning.
For example, if a device warns a driver only in a case when a device detects an object which a driver possibly overlooks, making a driver face a dangerous situation at a cross section and a driver overlooks such object which should be recognized by him/her, it is possible for a device to efficiently assist a driver for driving with safety.
Patent Document 1:
Japanese Unexamined Patent Publication No. 7-167668 (page 7, FIG. 1)
Patent Document 2:
Japanese Unexamined Patent Publication No. 2005-182307 (page 13, FIG. 4)